Report blobs shallow verify could not check apart from missing ones (closes #318)

Shallow snapshot verify counted every error from checking a blob or the
encrypted database as "missing" and printed the error nowhere, so a
permission error or an S3 403 read as data loss. Now only a not-found
answer from storage counts as missing. Any other error is reported as
could not be checked, with the error storage returned, in the text
report and under --json (the new unchecked list and
database_check_error field), and the run fails. Under --quiet, which
drops the report, each of those errors is logged as a warning on
stderr.

The database check moved into its own small function because the verify
function was at the linter's length limit.

Model: opus-5-5

README.md

@@ -293,8 +293,8 @@ needed.
 **`snapshot list`**: Show every snapshot known to this host — the union
 of the local index and the backup destination store — with timestamps
 and three sizes per snapshot (compressed remote size; total
-uncompressed chunk size; size of chunks newly referenced by that
-snapshot).
+uncompressed chunk size; size of the chunks that snapshot stored that
+were not stored before, recorded when its backup ran).
 
 Listing the destination store does **not** require the age secret key,
 so it works in vaultik's intended configuration, where the backed-up
@@ -307,8 +307,8 @@ only the hash, so hostname and snapshot name exist solely in the local
 index and in the encrypted per-snapshot database. Snapshots found only
 on the destination store are therefore listed as
 `<remote only:<abbreviated remote key>>` and show `<remote only>` in
-the uncompressed and "new chunk" columns, which can only be computed
-from the local index. Their timestamp and compressed size are real,
+the uncompressed and "new chunk" columns, which come only from the
+local index. Their timestamp and compressed size are real,
 read from the manifest.
 
 Snapshots in the local index with no counterpart on the destination

docs/DATAMODEL.md

@@ -119,6 +119,7 @@ Tracks backup snapshots.
 - `completed_at` (INTEGER) - Completion timestamp (NULL if in progress)
 - `file_count` (INTEGER) - Number of files in snapshot
 - `chunk_count` (INTEGER) - Number of chunks this snapshot stored that were not stored before
+- `new_chunk_size` (INTEGER) - Total size of those chunks before compression; `snapshot list` shows it as NEW CHUNK SIZE
 - `blob_count` (INTEGER) - Number of blobs this snapshot created
 - `total_size` (INTEGER) - Total size of all files
 - `blob_size` (INTEGER) - Total compressed size of all referenced blobs

internal/database/repositories.go

@@ -3,6 +3,7 @@ package database
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 )
 
@@ -60,22 +61,24 @@ func (r *Repositories) WithTx(ctx context.Context, fn TxFunc) error {
 
 	defer func() {
 		if p := recover(); p != nil {
-			rollbackErr := tx.Rollback()
-			if rollbackErr != nil {
-				Fatalf("failed to rollback transaction: %v", rollbackErr)
-			}
+			// The panic is the failure to report, so a rollback error
+			// is dropped.
+			_ = tx.Rollback()
 
 			panic(p)
-		} else if err != nil {
-			rollbackErr := tx.Rollback()
-			if rollbackErr != nil {
-				Fatalf("failed to rollback transaction: %v", rollbackErr)
-			}
 		}
 	}()
 
 	err = fn(ctx, tx)
 	if err != nil {
+		// Once ctx is cancelled, database/sql rolls the transaction
+		// back itself and Rollback returns sql.ErrTxDone.
+		rollbackErr := tx.Rollback()
+		if rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
+			return fmt.Errorf("%w; rolling back transaction: %w",
+				err, rollbackErr)
+		}
+
 		return err
 	}
 

internal/database/repositories_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"strings"
 	"testing"
 	"time"
 
@@ -235,6 +236,125 @@ func TestRepositoriesTransactionRollback(t *testing.T) {
 	}
 }
 
+// When the context is cancelled during the body, database/sql rolls the
+// transaction back itself, so WithTx's own rollback finds it already
+// done. WithTx must return the body's error alone, without that rollback.
+func TestRepositoriesTransactionContextCancelled(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	repos := database.NewRepositories(db)
+
+	err := repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+		file := &database.File{
+			Path:  "/test/cancelled_file.txt",
+			MTime: time.Now().Truncate(time.Second),
+			Size:  1024,
+			Mode:  0644,
+			UID:   1000,
+			GID:   1000,
+		}
+
+		err := repos.Files.Create(ctx, tx, file)
+		if err != nil {
+			return err
+		}
+
+		cancel()
+
+		// database/sql rolls back from a goroutine of its own; wait
+		// until it has, so the test does not depend on that race.
+		for {
+			_, err = tx.ExecContext(context.WithoutCancel(ctx), "SELECT 1")
+			if errors.Is(err, sql.ErrTxDone) {
+				return ctx.Err()
+			}
+
+			time.Sleep(time.Millisecond)
+		}
+	})
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected context.Canceled, got: %v", err)
+	}
+
+	if errors.Is(err, sql.ErrTxDone) {
+		t.Fatalf("the already-done rollback was reported: %v", err)
+	}
+
+	file, err := repos.Files.GetByPath(
+		context.Background(), "/test/cancelled_file.txt",
+	)
+	if err != nil {
+		t.Fatalf("error checking for file: %v", err)
+	}
+
+	if file != nil {
+		t.Error("file should not exist after the cancelled transaction")
+	}
+}
+
+// A body that ends the transaction itself with ROLLBACK makes WithTx's
+// own rollback fail. WithTx must return that failure together with the
+// body's error.
+func TestRepositoriesTransactionRollbackFails(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	repos := database.NewRepositories(db)
+
+	err := repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+		_, err := tx.ExecContext(ctx, "ROLLBACK")
+		if err != nil {
+			return err
+		}
+
+		return errIntentionalRollback
+	})
+	if !errors.Is(err, errIntentionalRollback) {
+		t.Fatalf("expected the body's error, got: %v", err)
+	}
+
+	if !strings.Contains(err.Error(), "rolling back transaction") {
+		t.Errorf("expected the failed rollback in the error, got: %v", err)
+	}
+}
+
+// When the body ends the transaction itself with ROLLBACK and then
+// panics, WithTx's own rollback fails; the panic must still reach the
+// caller.
+func TestRepositoriesTransactionPanicRollbackFails(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	repos := database.NewRepositories(db)
+
+	defer func() {
+		if recover() == nil {
+			t.Error("expected the body's panic to reach the caller")
+		}
+	}()
+
+	_ = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+		_, err := tx.ExecContext(ctx, "ROLLBACK")
+		if err != nil {
+			return err
+		}
+
+		panic(errIntentionalRollback)
+	})
+}
+
 func TestRepositoriesReadTransaction(t *testing.T) {
 	t.Parallel()
 

internal/database/schema/001.sql

@@ -86,6 +86,7 @@ CREATE TABLE IF NOT EXISTS snapshots (
     completed_at INTEGER,
     file_count INTEGER NOT NULL DEFAULT 0,
     chunk_count INTEGER NOT NULL DEFAULT 0,
+    new_chunk_size INTEGER NOT NULL DEFAULT 0,
     blob_count INTEGER NOT NULL DEFAULT 0,
     total_size INTEGER NOT NULL DEFAULT 0,
     blob_size INTEGER NOT NULL DEFAULT 0,

internal/database/snapshots.go

@@ -129,6 +129,7 @@ func (r *SnapshotRepository) UpdateExtendedStats(
 	compressionLevel int,
 	uploadBytes int64,
 	uploadDurationMs int64,
+	newChunkSize int64,
 ) error {
 	compressionRatio, err := r.extendedCompressionRatio(
 		ctx, tx, snapshotID, blobUncompressedSize,
@@ -143,18 +144,19 @@ func (r *SnapshotRepository) UpdateExtendedStats(
 		    compression_ratio = ?,
 		    compression_level = ?,
 		    upload_bytes = ?,
-		    upload_duration_ms = ?
+		    upload_duration_ms = ?,
+		    new_chunk_size = ?
 		WHERE id = ?
 	`
 
 	if tx != nil {
 		_, err = tx.ExecContext(ctx, query,
 			blobUncompressedSize, compressionRatio, compressionLevel,
-			uploadBytes, uploadDurationMs, snapshotID)
+			uploadBytes, uploadDurationMs, newChunkSize, snapshotID)
 	} else {
 		_, err = r.db.ExecWithLog(ctx, query,
 			blobUncompressedSize, compressionRatio, compressionLevel,
-			uploadBytes, uploadDurationMs, snapshotID)
+			uploadBytes, uploadDurationMs, newChunkSize, snapshotID)
 	}
 
 	if err != nil {
@@ -594,45 +596,24 @@ func (r *SnapshotRepository) GetSnapshotUncompressedChunkSize(
 	return totalSize, nil
 }
 
-// GetSnapshotNewChunkSize returns the sum of plaintext sizes of chunks that are
-// referenced by this snapshot but not by any earlier completed snapshot known to
-// the local database. The result is the marginal uncompressed data this snapshot
-// added to the dedup pool — i.e., the delta from prior snapshots.
+// GetSnapshotNewChunkSize returns the total plaintext size of the chunks the
+// snapshot's backup stored that were not stored before, as the backup
+// recorded it. It is not derived from the snapshot's files: a file's row is
+// shared by every snapshot that lists it and is rewritten when the file
+// changes, so it shows only the file's latest chunks.
 func (r *SnapshotRepository) GetSnapshotNewChunkSize(
 	ctx context.Context, snapshotID string,
 ) (int64, error) {
-	query := `
-		WITH this_snap_chunks AS (
-			SELECT DISTINCT fc.chunk_hash
-			FROM snapshot_files sf
-			JOIN file_chunks fc ON sf.file_id = fc.file_id
-			WHERE sf.snapshot_id = ?
-		),
-		prior_chunks AS (
-			SELECT DISTINCT fc.chunk_hash
-			FROM snapshots s
-			JOIN snapshot_files sf ON sf.snapshot_id = s.id
-			JOIN file_chunks fc ON fc.file_id = sf.file_id
-			WHERE s.completed_at IS NOT NULL
-			  AND s.id != ?
-			  AND s.started_at < (SELECT started_at FROM snapshots WHERE id = ?)
-		)
-		SELECT COALESCE(SUM(c.size), 0)
-		FROM chunks c
-		JOIN this_snap_chunks t ON c.chunk_hash = t.chunk_hash
-		WHERE c.chunk_hash NOT IN (SELECT chunk_hash FROM prior_chunks)
-	`
+	query := `SELECT new_chunk_size FROM snapshots WHERE id = ?`
 
-	var totalSize int64
+	var newChunkSize int64
 
-	err := r.db.conn.QueryRowContext(
-		ctx, query, snapshotID, snapshotID, snapshotID,
-	).Scan(&totalSize)
+	err := r.db.conn.QueryRowContext(ctx, query, snapshotID).Scan(&newChunkSize)
 	if err != nil {
 		return 0, fmt.Errorf("querying new chunk size: %w", err)
 	}
 
-	return totalSize, nil
+	return newChunkSize, nil
 }
 
 // GetIncompleteSnapshots returns all snapshots that haven't been completed

internal/log/tty_handler.go

@@ -10,6 +10,8 @@ import (
 	"sync"
 	"time"
 	"unicode"
+
+	"github.com/dustin/go-humanize"
 )
 
 // groupSeparator joins an open group path to an attribute key. This
@@ -304,18 +306,13 @@ func formatDuration(d time.Duration) string {
 	}
 }
 
-// formatBytes formats bytes in a human-readable way
+// formatBytes formats a byte count with humanize.Bytes, as every command
+// prints one. humanize.Bytes takes no negative count, so one is printed
+// as it is.
 func formatBytes(b int64) string {
-	const unit = 1024
-	if b < unit {
+	if b < 0 {
 		return fmt.Sprintf("%d B", b)
 	}
 
-	div, exp := int64(unit), 0
-	for n := b / unit; n >= unit; n /= unit {
-		div *= unit
-		exp++
-	}
-
-	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "KMGTPE"[exp])
+	return humanize.Bytes(uint64(b))
 }

internal/log/tty_handler_test.go

@@ -200,7 +200,8 @@ func TestTTYHandlerWithGroupQualifiesKeys(t *testing.T) {
 func TestTTYHandlerByteFormattingSurvivesGrouping(t *testing.T) {
 	t.Parallel()
 
-	const oneAndAHalfKiB = 1536
+	// Printed as "1.0 MB", in powers of 1000 like every other byte count.
+	const oneMegabyte = 1_000_000
 
 	for name, testCase := range map[string]struct {
 		derive func(*slog.Logger) *slog.Logger
@@ -223,13 +224,13 @@ func TestTTYHandlerByteFormattingSurvivesGrouping(t *testing.T) {
 			var buf bytes.Buffer
 
 			logger := slog.New(log.NewTTYHandler(&buf, debugHandlerOptions()))
-			testCase.derive(logger).Info("uploaded", "bytes", oneAndAHalfKiB)
+			testCase.derive(logger).Info("uploaded", "bytes", oneMegabyte)
 
 			line := ansiEscape.ReplaceAllString(buf.String(), "")
 
-			assert.Contains(t, line, testCase.key+"=1.5 KB",
+			assert.Contains(t, line, testCase.key+"=1.0 MB",
 				"a byte count must be human-readable however it is qualified")
-			assert.NotContains(t, line, strconv.Itoa(oneAndAHalfKiB),
+			assert.NotContains(t, line, strconv.Itoa(oneMegabyte),
 				"the raw number must not survive the formatting")
 		})
 	}

internal/snapshot/scanner.go

@@ -135,7 +135,9 @@ type ScannerConfig struct {
 // are counted per file: BytesScanned is the size of the new and changed
 // files, BytesSkipped that of the unchanged ones. FilesFailed counts the
 // new and changed files that phase 2 could not store; FilesScanned
-// includes them and BytesScanned does not.
+// includes them and BytesScanned does not. ChunksCreated counts the
+// chunks that were not already stored, and NewChunkSize is their total
+// size.
 type ScanResult struct {
 	FilesScanned   int
 	FilesSkipped   int
@@ -145,6 +147,7 @@ type ScanResult struct {
 	BytesSkipped   int64
 	BytesDeleted   int64
 	ChunksCreated  int
+	NewChunkSize   int64
 	BlobsCreated   int
 	BlobsUploaded  int
 	BytesUploaded  int64
@@ -1866,11 +1869,12 @@ func (s *Scanner) processFileStreaming(
 	return nil
 }
 
-// updateChunkStats counts a chunk that was not already stored. The scan
-// result's file counts, BytesScanned and BytesSkipped are not touched
-// here: the scan phase counts each file once.
+// updateChunkStats counts a chunk that was not already stored, and its
+// size. The scan result's file counts, BytesScanned and BytesSkipped are
+// not touched here: the scan phase counts each file once.
 func (s *Scanner) updateChunkStats(chunkSize int64, result *ScanResult) {
 	result.ChunksCreated++
+	result.NewChunkSize += chunkSize
 
 	if s.progress != nil {
 		s.progress.GetStats().ChunksCreated.Add(1)

internal/snapshot/snapshot.go

@@ -199,6 +199,7 @@ func (sm *SnapshotManager) UpdateSnapshotStatsExtended(
 			stats.CompressionLevel,
 			stats.BytesUploaded,
 			stats.UploadDurationMs,
+			stats.NewChunkSize,
 		)
 	})
 }
@@ -906,6 +907,7 @@ type ExtendedBackupStats struct {
 	BlobUncompressedSize int64 // Total uncompressed size of all referenced blobs
 	CompressionLevel     int   // Compression level used for this snapshot
 	UploadDurationMs     int64 // Total milliseconds spent uploading to S3
+	NewChunkSize         int64 // Total size of the chunks counted in ChunksCreated
 }
 
 // deleteOtherSnapshots deletes all snapshots except the current one

internal/vaultik/destination_validation_test.go

@@ -161,13 +161,14 @@ func TestVerifyManifestBlobsRejectsShortHash(t *testing.T) {
 		Blobs: []snapshot.BlobInfo{{Hash: "abc", CompressedSize: 1}},
 	}
 
-	verified, missing, mismatched, missingSize, err :=
+	verified, missing, mismatched, missingSize, unchecked, err :=
 		v.verifyManifestBlobs(manifest, &VerifyOptions{JSON: true})
 	require.ErrorIs(t, err, errInvalidBlobHash)
 	require.Zero(t, verified)
 	require.Zero(t, missing)
 	require.Zero(t, mismatched)
 	require.Zero(t, missingSize)
+	require.Empty(t, unchecked)
 }
 
 // TestVerifyBlobChunksRejectsNegativeLength proves a blob_chunks row with a

internal/vaultik/helpers.go

@@ -89,22 +89,6 @@ type SnapshotInfo struct {
 	RemotePresent    *bool            `json:"remote_present"`
 }
 
-// formatBytes formats bytes in a human-readable format
-func formatBytes(bytes int64) string {
-	const unit = 1024
-	if bytes < unit {
-		return fmt.Sprintf("%d B", bytes)
-	}
-
-	div, exp := int64(unit), 0
-	for n := bytes / unit; n >= unit; n /= unit {
-		div *= unit
-		exp++
-	}
-
-	return fmt.Sprintf("%.1f %cB", float64(bytes)/float64(div), "KMGTPE"[exp])
-}
-
 // parseSnapshotTimestamp extracts the timestamp from a snapshot ID
 // Format: hostname_snapshotname_2026-01-12T14:41:15Z
 func parseSnapshotTimestamp(snapshotID string) (time.Time, error) {

internal/vaultik/new_chunk_size_test.go

@@ -0,0 +1,133 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"maps"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/chunker"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestNewChunkSizeOfChangedFileStaysFixed covers
+// https://git.eeqj.de/sneak/vaultik/issues/311. A backup whose only change
+// is a modified file lists the size of the chunks that change added as its
+// NEW CHUNK SIZE, and a later backup that changes the file again leaves
+// every earlier snapshot's figure as it was. The file's row in the local
+// index is shared by all three snapshots and rewritten by each backup.
+func TestNewChunkSizeOfChangedFileStaysFixed(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+	changedPath := filepath.Join(dataDir, "changed.bin")
+
+	ctx := context.Background()
+	files := writeFaultSourceTree(t, fs, dataDir)
+	cfg := changedFileConfig(dataDir, dbPath)
+
+	appendRandomBytes(t, fs, files, changedPath, appendedFileSize)
+
+	store, err := storage.NewFileStorer(filepath.Join(tempDir, "remote"))
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
+
+	require.NoError(t, backUp(v, "first"))
+
+	firstFiles := maps.Clone(files)
+	firstID := localSnapshotID(ctx, t, repos, "first")
+
+	appendRandomBytes(t, fs, files, changedPath, faultChunkSize)
+	require.NoError(t, backUp(v, "second"))
+
+	secondID := localSnapshotID(ctx, t, repos, "second")
+	secondAdded := sizeOfNewChunks(t, files, firstFiles)
+	require.Positive(t, secondAdded)
+	assert.Equal(t, secondAdded, listedNewChunkSizes(t, v)[secondID],
+		"the second snapshot must count the chunks the change added")
+
+	appendRandomBytes(t, fs, files, changedPath, faultChunkSize)
+	require.NoError(t, backUp(v, "third"))
+
+	sizes := listedNewChunkSizes(t, v)
+	assert.Equal(t, sizeOfNewChunks(t, firstFiles, nil), sizes[firstID],
+		"a later backup must not change the first snapshot's figure")
+	assert.Equal(t, secondAdded, sizes[secondID],
+		"a later backup must not change the second snapshot's figure")
+}
+
+// sizeOfNewChunks returns the total size of the distinct chunks of the
+// files in after that no file in before has, cut the way the backup cuts
+// them.
+func sizeOfNewChunks(t *testing.T, after, before map[string][]byte) int64 {
+	t.Helper()
+
+	known := make(map[string]bool)
+	for _, chunk := range chunksOf(t, before) {
+		known[chunk.Hash] = true
+	}
+
+	var total int64
+
+	for _, chunk := range chunksOf(t, after) {
+		if !known[chunk.Hash] {
+			known[chunk.Hash] = true
+			total += chunk.Size
+		}
+	}
+
+	return total
+}
+
+// chunksOf returns the chunks of every file in files.
+func chunksOf(t *testing.T, files map[string][]byte) []chunker.Chunk {
+	t.Helper()
+
+	c := chunker.NewChunker(faultChunkSize)
+
+	var all []chunker.Chunk
+
+	for _, content := range files {
+		chunks, err := c.ChunkReader(bytes.NewReader(content))
+		require.NoError(t, err)
+
+		all = append(all, chunks...)
+	}
+
+	return all
+}
+
+// listedNewChunkSizes runs `snapshot list --json` and returns each listed
+// snapshot's new_chunk_size by snapshot ID.
+func listedNewChunkSizes(t *testing.T, v *vaultik.Vaultik) map[string]int64 {
+	t.Helper()
+
+	var out bytes.Buffer
+
+	v.Stdout = &out
+	require.NoError(t, v.ListSnapshots(true))
+
+	sizes := make(map[string]int64)
+	for _, row := range decodeListJSON(t, out.String()) {
+		sizes[row.ID] = row.NewChunkSize
+	}
+
+	return sizes
+}

internal/vaultik/shallow_verify_test.go

@@ -4,15 +4,20 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"io"
 	"os"
+	"path"
 	"path/filepath"
+	"slices"
 	"testing"
 
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/require"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
 	"sneak.berlin/go/vaultik/internal/ui"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -151,6 +156,224 @@ func TestShallowVerifyDetectsMissingDatabase(t *testing.T) {
 		"shallow verify must fail when db.zst.age is absent")
 }
 
+// errStatDenied stands in for any storage error other than not-found: a
+// permission error, an S3 403, a dropped connection.
+var errStatDenied = errors.New("injected stat failure")
+
+// statFailingStorer fails Stat with errStatDenied for the keys in
+// failKeys and passes every other call to the wrapped Storer.
+type statFailingStorer struct {
+	storage.Storer
+
+	failKeys []string
+}
+
+func (s statFailingStorer) Stat(
+	ctx context.Context, key string,
+) (*storage.ObjectInfo, error) {
+	if slices.Contains(s.failKeys, key) {
+		return nil, fmt.Errorf("stat %q: %w", key, errStatDenied)
+	}
+
+	return s.Storer.Stat(ctx, key)
+}
+
+// TestShallowVerifyReportsStatErrorsApartFromMissing backs up a real
+// snapshot, deletes one blob, and makes storage fail Stat with an error
+// other than not-found for a second blob and for the encrypted database.
+// Only the deleted blob may be counted as missing. The second blob and
+// the database must be reported as could not be checked, with the error
+// storage returned, and verify must fail, in the text output and under
+// --json.
+func TestShallowVerifyReportsStatErrorsApartFromMissing(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+
+	dataDir := filepath.Join(tempDir, "source")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	chunkSize := int64(32 * 1024)
+	maxBlobSize := int64(128 * 1024)
+
+	// Random content, so the snapshot spans several blobs.
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+	appendRandomBytes(t, fs, map[string][]byte{},
+		filepath.Join(dataDir, "data.bin"), maxBlobSize*4)
+
+	ctx := context.Background()
+
+	cfg, storer, snapshotID := runFileStorageBackup(
+		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)
+
+	blobKeys := storedBlobKeys(t, storeDir)
+	require.GreaterOrEqual(t, len(blobKeys), 2, "expected at least two blobs")
+
+	missingKey, uncheckedKey := blobKeys[0], blobKeys[1]
+	missingHash, uncheckedHash := path.Base(missingKey), path.Base(uncheckedKey)
+
+	require.NoError(t, os.Remove(filepath.Join(storeDir, missingKey)))
+
+	dbKey := "metadata/" + snapshot.RemoteSnapshotKey(snapshotID) + "/db.zst.age"
+	failing := statFailingStorer{
+		Storer:   storer,
+		failKeys: []string{uncheckedKey, dbKey},
+	}
+
+	newVerifier := func(out io.Writer) *vaultik.Vaultik {
+		v := &vaultik.Vaultik{
+			Config:  cfg,
+			Storage: failing,
+			Fs:      fs,
+			Stdout:  out,
+			Stderr:  io.Discard,
+			UI:      ui.NewWithColor(io.Discard, false),
+		}
+		v.SetContext(ctx)
+
+		return v
+	}
+
+	var out bytes.Buffer
+
+	err := newVerifier(&out).VerifySnapshotWithOptions(
+		snapshotID, &vaultik.VerifyOptions{JSON: true})
+	require.Error(t, err)
+
+	result := decodeVerifyResult(t, out.Bytes())
+	require.Equal(t, "failed", result.Status)
+	require.Equal(t, 1, result.Missing, "only the deleted blob is missing")
+	require.Equal(t, result.BlobCount-2, result.Verified)
+	require.Len(t, result.Unchecked, 1)
+	require.Equal(t, uncheckedHash, result.Unchecked[0].Hash)
+	require.Contains(t, result.Unchecked[0].Error, errStatDenied.Error())
+	require.False(t, result.DatabaseMissing,
+		"a database that could not be checked is not missing")
+	require.Contains(t, result.DatabaseCheckError, errStatDenied.Error())
+
+	out.Reset()
+	err = newVerifier(&out).VerifySnapshotWithOptions(
+		snapshotID, &vaultik.VerifyOptions{})
+	require.Error(t, err)
+
+	text := out.String()
+	require.Contains(t, text, "Missing: "+missingHash)
+	require.NotContains(t, text, "Missing: "+uncheckedHash)
+	require.Contains(t, text, "Could not check: "+uncheckedHash)
+	require.Contains(t, text, "Encrypted database:       could not be checked")
+	require.Contains(t, text, errStatDenied.Error())
+	require.Contains(t, text, "FAILED")
+}
+
+// TestShallowVerifyQuietFailsOnStatErrorAlone backs up a healthy snapshot,
+// then makes storage fail Stat, with an error other than not-found, for
+// one blob alone and then for the encrypted database alone. Each run must
+// fail verify, and under --quiet, which drops the report, the error
+// storage returned must still reach stderr.
+//
+//nolint:paralleltest // captureProcessStderr replaces os.Stderr
+func TestShallowVerifyQuietFailsOnStatErrorAlone(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+
+	dataDir := filepath.Join(tempDir, "source")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	chunkSize := int64(32 * 1024)
+	maxBlobSize := int64(128 * 1024)
+
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(dataDir, "data.bin"),
+		bytesPattern("shallow-quiet-", int(maxBlobSize*2)), 0o644))
+
+	ctx := context.Background()
+
+	cfg, storer, snapshotID := runFileStorageBackup(
+		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)
+
+	newQuietVerifier := func(s storage.Storer) *vaultik.Vaultik {
+		v := &vaultik.Vaultik{
+			Config:  cfg,
+			Storage: s,
+			Fs:      fs,
+			Stdout:  io.Discard,
+			Stderr:  io.Discard,
+			UI:      ui.NewWithColor(io.Discard, false),
+		}
+		v.SetContext(ctx)
+		v.UI.SetQuiet(true)
+
+		return v
+	}
+
+	require.NoError(t,
+		newQuietVerifier(storer).VerifySnapshotWithOptions(
+			snapshotID, &vaultik.VerifyOptions{}),
+		"shallow verify should pass on a healthy snapshot")
+
+	blobKeys := storedBlobKeys(t, storeDir)
+	require.NotEmpty(t, blobKeys)
+
+	dbKey := "metadata/" + snapshot.RemoteSnapshotKey(snapshotID) + "/db.zst.age"
+
+	for _, failKey := range []string{blobKeys[0], dbKey} {
+		v := newQuietVerifier(statFailingStorer{
+			Storer:   storer,
+			failKeys: []string{failKey},
+		})
+
+		var err error
+
+		stderr := captureProcessStderr(t, func() {
+			err = v.VerifySnapshotWithOptions(
+				snapshotID, &vaultik.VerifyOptions{})
+		})
+
+		require.Error(t, err,
+			"verify must fail when %s could not be checked", failKey)
+		require.Contains(t, stderr, errStatDenied.Error(),
+			"under --quiet the error for %s must still reach stderr", failKey)
+	}
+}
+
+// storedBlobKeys returns the storage key of every blob file under
+// storeDir, sorted.
+func storedBlobKeys(t *testing.T, storeDir string) []string {
+	t.Helper()
+
+	var keys []string
+
+	err := filepath.Walk(filepath.Join(storeDir, "blobs"),
+		func(p string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			if info.IsDir() {
+				return nil
+			}
+
+			rel, err := filepath.Rel(storeDir, p)
+			if err != nil {
+				return err
+			}
+
+			keys = append(keys, filepath.ToSlash(rel))
+
+			return nil
+		})
+	require.NoError(t, err)
+
+	return keys
+}
+
 // growOneBlob appends bytes to the first blob file found under blobsDir,
 // changing its on-disk size so it no longer matches the manifest.
 func growOneBlob(t *testing.T, fs afero.Fs, blobsDir string) {

internal/vaultik/snapshot.go

@@ -14,6 +14,7 @@ import (
 
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
@@ -209,6 +210,7 @@ type snapshotStats struct {
 	totalFiles         int
 	totalBytes         int64
 	totalChunks        int
+	newChunkSize       int64
 	totalBlobs         int
 	totalBytesSkipped  int64
 	totalFilesSkipped  int
@@ -341,6 +343,7 @@ func (v *Vaultik) scanAllDirectories(
 		stats.totalFiles += result.FilesScanned
 		stats.totalBytes += result.BytesScanned
 		stats.totalChunks += result.ChunksCreated
+		stats.newChunkSize += result.NewChunkSize
 		stats.totalBlobs += result.BlobsCreated
 		stats.totalFilesSkipped += result.FilesSkipped
 		stats.totalFilesFailed += result.FilesFailed
@@ -403,6 +406,7 @@ func (v *Vaultik) finalizeSnapshotMetadata(
 		BlobUncompressedSize: stats.blobUncompressedSize,
 		CompressionLevel:     v.Config.CompressionLevel,
 		UploadDurationMs:     stats.uploadDuration.Milliseconds(),
+		NewChunkSize:         stats.newChunkSize,
 	}
 
 	err = v.SnapshotManager.UpdateSnapshotStatsExtended(v.ctx, snapshotID, extStats)
@@ -633,7 +637,7 @@ func (v *Vaultik) confirmAndExecutePurge(
 			v.stdoutf("  %s (%s, %s)\n",
 				snap.ID,
 				snap.Timestamp.Format("2006-01-02 15:04:05"),
-				formatBytes(snap.CompressedSize))
+				ubytes(snap.CompressedSize))
 		}
 	}
 
@@ -774,18 +778,10 @@ func (v *Vaultik) VerifySnapshotWithOptions(
 		v.stdoutf("Checking blob presence and sizes...\n")
 	}
 
-	// A snapshot is only restorable if its encrypted database is present
-	// alongside the blobs. Shallow verify checks that the object exists; it
-	// does not decrypt it (that is deep verify's job).
-	dbPath := fmt.Sprintf("metadata/%s/db.zst.age", remoteKey)
+	v.checkSnapshotDatabase(remoteKey, result)
 
-	_, dbErr := v.Storage.Stat(v.ctx, dbPath)
-	if dbErr != nil {
-		result.DatabaseMissing = true
-	}
-
-	result.Verified, result.Missing, result.Mismatched, result.MissingSize, err =
-		v.verifyManifestBlobs(manifest, opts)
+	result.Verified, result.Missing, result.Mismatched, result.MissingSize,
+		result.Unchecked, err = v.verifyManifestBlobs(manifest, opts)
 	if err != nil {
 		if opts.JSON {
 			result.Status = verifyStatusFailed
@@ -822,25 +818,46 @@ func (v *Vaultik) printVerifyHeader(snapshotID string, opts *VerifyOptions) {
 	}
 }
 
+// checkSnapshotDatabase records in result whether the snapshot's
+// encrypted database is missing or could not be checked. A snapshot is
+// only restorable if its database is present alongside the blobs.
+// Shallow verify checks that the object exists; it does not decrypt it
+// (that is deep verify's job).
+func (v *Vaultik) checkSnapshotDatabase(remoteKey string, result *VerifyResult) {
+	dbPath := fmt.Sprintf("metadata/%s/db.zst.age", remoteKey)
+
+	_, err := v.Storage.Stat(v.ctx, dbPath)
+
+	switch {
+	case errors.Is(err, storage.ErrNotFound):
+		result.DatabaseMissing = true
+	case err != nil:
+		result.DatabaseCheckError = err.Error()
+	}
+}
+
 // verifyManifestBlobs checks that each blob in the manifest is present in
 // storage with the size the manifest records, returning the counts of
 // blobs that were present with the right size, absent, and present but the
-// wrong size, plus the total bytes of the absent blobs. It does not read
-// blob contents; deep verification (RunDeepVerify) does that. The size
-// comparison matches the deep path (see verifyBlobExistenceFromDB).
+// wrong size, the total bytes of the absent blobs, and the blobs it could
+// not check because storage returned an error other than not-found. It
+// does not read blob contents; deep verification (RunDeepVerify) does
+// that. The size comparison matches the deep path (see
+// verifyBlobExistenceFromDB).
 func (v *Vaultik) verifyManifestBlobs(
 	manifest *snapshot.Manifest, opts *VerifyOptions,
-) (int, int, int, int64, error) {
+) (int, int, int, int64, []UncheckedBlob, error) {
 	var (
 		verified, missing, mismatched int
 		missingSize                   int64
+		unchecked                     []UncheckedBlob
 	)
 
 	for _, blob := range manifest.Blobs {
 		// The manifest is unauthenticated, so its blob hashes are checked
 		// before being spliced into a storage path.
 		if !isBlobHash(blob.Hash) {
-			return 0, 0, 0, 0, fmt.Errorf("%w: %s",
+			return 0, 0, 0, 0, nil, fmt.Errorf("%w: %s",
 				errInvalidBlobHash, shortHash(blob.Hash))
 		}
 
@@ -849,7 +866,7 @@ func (v *Vaultik) verifyManifestBlobs(
 
 		stat, err := v.Storage.Stat(v.ctx, blobPath)
 		switch {
-		case err != nil:
+		case errors.Is(err, storage.ErrNotFound):
 			if !opts.JSON && !v.UI.Quiet() {
 				v.stdoutf("  Missing: %s (%s)\n",
 					blob.Hash, ubytes(blob.CompressedSize))
@@ -857,6 +874,13 @@ func (v *Vaultik) verifyManifestBlobs(
 
 			missing++
 			missingSize += blob.CompressedSize
+		case err != nil:
+			if !opts.JSON && !v.UI.Quiet() {
+				v.stdoutf("  Could not check: %s (%v)\n", blob.Hash, err)
+			}
+
+			unchecked = append(unchecked,
+				UncheckedBlob{Hash: blob.Hash, Error: err.Error()})
 		case stat.Size != blob.CompressedSize:
 			if !opts.JSON && !v.UI.Quiet() {
 				v.stdoutf("  Wrong size: %s (store has %s, manifest lists %s)\n",
@@ -869,7 +893,7 @@ func (v *Vaultik) verifyManifestBlobs(
 		}
 	}
 
-	return verified, missing, mismatched, missingSize, nil
+	return verified, missing, mismatched, missingSize, unchecked, nil
 }
 
 // formatVerifyResult outputs the final verification results as JSON or
@@ -890,9 +914,19 @@ func (v *Vaultik) formatVerifyResult(
 		return v.outputVerifyJSON(result)
 	}
 
-	// Under --quiet a failure is still returned, and the cli layer
-	// prints it on stderr.
-	if !v.UI.Quiet() {
+	// --quiet drops the report but not the errors storage returned, which
+	// are logged on stderr. A failure is still returned either way, and
+	// the cli layer prints it on stderr.
+	if v.UI.Quiet() {
+		for _, blob := range result.Unchecked {
+			log.Warn("Could not check blob", "blob", blob.Hash, "error", blob.Error)
+		}
+
+		if result.DatabaseCheckError != "" {
+			log.Warn("Could not check the encrypted database",
+				"snapshot", result.SnapshotID, "error", result.DatabaseCheckError)
+		}
+	} else {
 		v.printVerifySummary(result, failure)
 	}
 
@@ -918,10 +952,19 @@ func (v *Vaultik) printVerifySummary(result *VerifyResult, failure string) {
 		v.stdoutf("  Wrong size:               %d blobs\n", result.Mismatched)
 	}
 
+	if len(result.Unchecked) > 0 {
+		v.stdoutf("  Could not check:          %d blobs\n", len(result.Unchecked))
+	}
+
 	if result.DatabaseMissing {
 		v.stdoutf("  Encrypted database:       missing\n")
 	}
 
+	if result.DatabaseCheckError != "" {
+		v.stdoutf("  Encrypted database:       could not be checked (%s)\n",
+			result.DatabaseCheckError)
+	}
+
 	v.stdoutf("  Status:       ")
 
 	if failure != "" {
@@ -949,10 +992,19 @@ func shallowVerifyFailure(result *VerifyResult) string {
 			fmt.Sprintf("%d blobs have the wrong size", result.Mismatched))
 	}
 
+	if len(result.Unchecked) > 0 {
+		parts = append(parts, fmt.Sprintf("%d blobs could not be checked",
+			len(result.Unchecked)))
+	}
+
 	if result.DatabaseMissing {
 		parts = append(parts, "the encrypted database is missing")
 	}
 
+	if result.DatabaseCheckError != "" {
+		parts = append(parts, "the encrypted database could not be checked")
+	}
+
 	return strings.Join(parts, "; ")
 }
 

internal/vaultik/snapshot_list.go

@@ -553,8 +553,8 @@ func (v *Vaultik) printSnapshotTable(snapshots []SnapshotInfo) error {
 
 		if snap.LocallyTracked {
 			id = snap.ID.String()
-			uncompressed = formatBytes(snap.UncompressedSize)
-			newChunks = formatBytes(snap.NewChunkSize)
+			uncompressed = ubytes(snap.UncompressedSize)
+			newChunks = ubytes(snap.NewChunkSize)
 		} else {
 			id = formatRemoteOnlyID(snap.RemoteKey)
 			uncompressed = remoteOnlyCell
@@ -564,7 +564,7 @@ func (v *Vaultik) printSnapshotTable(snapshots []SnapshotInfo) error {
 		_, err = fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n",
 			id,
 			snap.Timestamp.Format("2006-01-02 15:04:05"),
-			formatBytes(snap.CompressedSize),
+			ubytes(snap.CompressedSize),
 			uncompressed,
 			newChunks)
 		if err != nil {

internal/vaultik/snapshot_list_test.go

@@ -212,8 +212,8 @@ const (
 	listConfiguredName = "home"
 	listLocalID        = "testhost_home_2026-03-01T10:00:00Z"
 	listRemoteID       = "otherhost_media_2026-03-02T11:22:33Z"
-	// fiveMegabytes formats as "5.0 MB" through formatBytes.
-	fiveMegabytes = 5 * 1024 * 1024
+	// fiveMegabytes is printed as "5.0 MB" by every command.
+	fiveMegabytes = 5_000_000
 )
 
 // TestListSnapshots_RemoteWithoutSecretKey is the regression guard for
@@ -306,6 +306,48 @@ func TestListSnapshots_RemoteOnlyRowRendering(t *testing.T) {
 		"are not in the local index")
 }
 
+// TestSnapshotListAndPurgePrintSizesLikeRemoteInfo checks that the
+// `snapshot list` table and the purge listing print a byte count the way
+// `remote info` does: in powers of 1000, as the MB label says.
+func TestSnapshotListAndPurgePrintSizesLikeRemoteInfo(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	const wantSize = "5.0 MB" // fiveMegabytes
+
+	env := newListEnv(t)
+
+	// A remote-only snapshot: `snapshot list` and `remote info` both take
+	// its size from the manifest.
+	remoteKey := env.addRemote(t, listRemoteID,
+		time.Date(2026, 3, 2, 11, 22, 33, 0, time.UTC))
+
+	// A locally tracked snapshot of the same size for the purge to list.
+	// The purge prints the snapshot's blob size, the last argument here.
+	start := time.Date(2026, 3, 1, 10, 0, 0, 0, time.UTC)
+	env.addLocal(t, listLocalID, start)
+	env.addRemote(t, listLocalID, start)
+	require.NoError(t, env.v.Repositories.Snapshots.UpdateCounts(
+		context.Background(), nil, listLocalID, 0, 0, 0, 0, fiveMegabytes))
+
+	require.NoError(t, env.v.RemoteInfo(false))
+	assert.Contains(t, findTableRow(t, env.stdout.String(), remoteKey[:16]),
+		wantSize, "remote info")
+
+	env.stdout.Reset()
+	require.NoError(t, env.v.ListSnapshots(false))
+	assert.Contains(t, findTableRow(t, env.stdout.String(),
+		"<remote only:"+remoteKey[:12]+">"), wantSize, "snapshot list")
+
+	// Without --force and with nothing on stdin the purge lists what it
+	// would delete, reads no confirmation, and deletes nothing.
+	env.stdout.Reset()
+	require.NoError(t, env.v.PurgeSnapshotsWithOptions(
+		&vaultik.SnapshotPurgeOptions{OlderThan: "1d"}))
+	assert.Contains(t, findTableRow(t, env.stdout.String(), listLocalID),
+		wantSize, "snapshot purge")
+}
+
 // findTableRow returns the single output line containing needle.
 func findTableRow(t *testing.T, out, needle string) string {
 	t.Helper()
@@ -445,6 +487,7 @@ type listJSONRow struct {
 	RemoteKey      string `json:"remote_key"`
 	Timestamp      string `json:"timestamp"`
 	CompressedSize int64  `json:"compressed_size"`
+	NewChunkSize   int64  `json:"new_chunk_size"`
 	LocallyTracked bool   `json:"locally_tracked"`
 	RemotePresent  *bool  `json:"remote_present"`
 }

internal/vaultik/verify.go

@@ -57,13 +57,27 @@ type VerifyResult struct {
 	Missing     int    `json:"missing"`
 	MissingSize int64  `json:"missing_size,omitempty"`
 	Mismatched  int    `json:"mismatched,omitempty"`
+	// Unchecked lists the blobs shallow verify could not check, because
+	// storage answered with an error other than not-found, so whether
+	// they are present is unknown.
+	Unchecked []UncheckedBlob `json:"unchecked,omitempty"`
 	// DatabaseMissing is set by shallow verify when the snapshot's
 	// encrypted database (metadata/<key>/db.zst.age) is absent, which
 	// makes the snapshot unrestorable regardless of the blobs.
 	DatabaseMissing bool `json:"database_missing,omitempty"`
+	// DatabaseCheckError is set by shallow verify to the error storage
+	// returned when the encrypted database could not be checked.
+	DatabaseCheckError string `json:"database_check_error,omitempty"`
 	ErrorMessage       string `json:"error,omitempty"`
 }
 
+// UncheckedBlob is a blob shallow verify could not check, with the error
+// storage returned for it.
+type UncheckedBlob struct {
+	Hash  string `json:"hash"`
+	Error string `json:"error"`
+}
+
 // deepVerifyFailure records a failure in the result and returns it appropriately
 func (v *Vaultik) deepVerifyFailure(
 	result *VerifyResult, opts *VerifyOptions, msg string, err error,